Infrared imaging cameras are used in a variety of situations. For example, infrared imaging cameras are often used during maintenance inspections to thermally inspect equipment. Example equipment may include rotating machinery, electrical panels, or rows of circuit breakers, among other types of equipment. Infrared inspections can detect equipment hot spots such as overheating machinery or electrical components, helping to ensure timely repair or replacement of the overheating equipment before a more significant problem develops.
Depending on the configuration of the camera, the infrared imaging camera may also generate a visible light image of the same object. The camera may display the infrared image and the visible light image in a coordinated manner, for example, to help an operator interpret the thermal image generated by the thermal imaging camera.
Visible light and/or infrared imaging has been applied to the field of gas imaging, in which a user will inspect a target scene for the presence of a target gas. In a typical procedure, a user will illuminate the target scene with light of a wavelength that is absorbed by the target gas. In theory, the light incident on the target scene will either encounter the target gas and be at least partially absorbed, or will be scattered back to the camera at substantially full intensity from various portions of the target scene. Thus, if the camera detects substantially the full intensity of light of the illuminating wavelength from a portion of the target scene, such portion of the scene will be assumed to not comprise the target gas, as the light was not significantly absorbed. Conversely, illuminated portions of the target scene from which the camera does not detect or detects attenuated amounts of light of the illuminating wavelength are assumed to comprise the target gas, since the absence of backscattered light is indicative of the absorption properties of the gas.
These systems can be difficult to use effectively in the field due to varying background conditions that prevent or interfere with the backscattered illuminating light energy. For example, where no scattering background is present (e.g., sky in the background) there is no backscattered energy at all. In a similar manner, if the background is too far or angled away from the illuminating light source, the backscattered signal may be too weak to create a noticeable gas “shadow.” This can be problematic because, where the backscatter is too weak, the weak or otherwise lack of gas shadow can cause a user to misinterpret the resulting image.
For example, if there is not an appropriate background for adequately scattering unabsorbed light toward the camera, the camera operator may falsely assume that the target gas is present in the target scene and is absorbing the illuminating light, since none of the light is scattered back toward the camera. On the other hand, in a setting in which backscatter is unlikely due to the background of the scene, a user may misinterpret a lack of detected backscattered light as an insufficient background as opposed to the target gas truly present in the target scene. In other examples, a background comprising angled or rounded surfaces can act to scatter light in directions away from the camera, resulting in a lack of backscattered energy incident on the camera in the absence of an absorbing target gas.